5-(Trifluoro­meth­oxy)isatin

Schutte, M.; Pretorius, C.; Visser, H.G.; Roodt, A.

doi:10.1107/S1600536812044297

organic compounds

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ISSN: 2056-9890

Volume 68| Part 12| December 2012| Page o3472

doi:10.1107/S1600536812044297

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5-(Trifluoromethoxy)isatin

M. Schutte,^a ^* C. Pretorius,^a H.G. Visser ^a and A. Roodt ^a

^aDepartment of Chemistry, University of the Free State, PO Box 339, Bloemfontein, 9301, South Africa
^*Correspondence e-mail: schuttem@ufs.ac.za

(Received 17 September 2012; accepted 25 October 2012; online 28 November 2012)

The title compound [systematic name: 5-(trifluoromethoxy)-1H-indole-2,3-dione], C₉H₄F₃NO₃, crystallized with two molecules in the asymmetric unit. Intermolecular N—H⋯O hydrogen bonds link the molecules to form layers parallel to the ab plane. In addition, π–π stacking interactions are observed with a centroid–centroid distance of 3.721 (1) Å. The near planarity of the two isatin ring systems is illustrated by by the maximum deviations of 0.023 (1) and 0.025 (1) Å for the N atom in each case.

Related literature

For similar structures and background information on isatin as a biological agent, see Schutte et al. (2012 ); Garden et al. (2006 ); Goldschmidt & Llewellyn (1950 ); Frolova et al. (1988 ); Wei et al. (2004 ); Palmer et al. (1987 ); Akkurt et al. (2006 ). For reaction kinetic data on similar structures, see: Schutte et al. (2011 ).

Experimental

Crystal data

C₉H₄F₃NO₃
M_r = 231.13
Monoclinic, P 2₁ /n
a = 14.329 (5) Å
b = 6.082 (5) Å
c = 20.401 (5) Å
β = 91.608 (5)°
V = 1777.2 (16) Å³
Z = 8
Mo Kα radiation
μ = 0.17 mm⁻¹
T = 100 K
0.51 × 0.18 × 0.10 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.152, T_max = 0.394
26198 measured reflections
4428 independent reflections
3513 reflections with I > 2σ(I)
R_int = 0.029

Refinement

R[F² > 2σ(F²)] = 0.036
wR(F²) = 0.102
S = 1.04
4418 reflections
297 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O4ⁱ	0.84 (2)	1.99 (2)	2.7615 (18)	152.8 (18)
N2—H2⋯O1ⁱⁱ	0.89 (2)	2.03 (2)	2.8776 (18)	157.4 (19)
N2—H2⋯O4ⁱⁱⁱ	0.89 (2)	2.55 (2)	2.9850 (18)	111.2 (16)
C16—H16⋯F3ⁱ	0.93	2.39	3.171 (2)	142
C18—H18⋯O2^iv	0.93	2.47	3.327 (3)	153
Symmetry codes: (i) x, y-1, z; (ii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) -x+1, -y+1, -z+1.

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812044297/fy2072sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812044297/fy2072Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812044297/fy2072Isup3.cml

checkCIF report

Comment top

5-(Trifluoromethoxy)isatin crystallized in the P2₁/n spacegroup and with two independent molecules in the asymmetric unit. The use of 5-(trifluormethoxy)isatin forms part of a current study, where water soluble O,O'-donor bidentate ligands are coordinated to the rhenium tricarbonyl core in order to study the reactivity and activation of these potential radiopharmaceutical compounds. Previous studies have shown that the O,O'-bidenate ligands activate the Re(I) core to a great extent and we would like to explore this further (Schutte et al. (2011). The isatin molecule also has a variety of biological activities. It can act as an anticonvulsant agent, it has sedative effects but can also cause anxiety. Palmer et al., 1987; Goldschmidt & Llewellyn, 1950; Wei et al., 2004; Frolova et al., 1988; Akkurt et al., 2006). Due to its diverse pharmacological properties, a lot of interest has been shown in the isatin molecule and its derivatives. All bond lengths and angles compare well to the structure of N-benzylisatin reported by Schutte et al. (2012). Five intermolecular hydrogen interactions are observed in the structure (C—H···O, N—H···O and C—H···F) as well as π-π stacking with a centroid to centroid distance of 3.721 (1) Å. The molecules pack in a head to head fashion in alternating layers with the benzyl ring overlapping with the next molecules' pyrrolidinedione ring and vice versa. The π-π stacking and the packing in the unit cell are illustrated in Figure 2. The planarity of the ring systems, N1—C11—C12—C13—C14—C15—C16—C17—C18 and N2—C21—C22—C23—C24—C25—C26—C27—C28, are illustrated by very small deviations of all the atoms from these planes, with the largest deviations 0.023 (1) Å for N1 and 0.025 (1) for N2 respectively.

Related literature top

For similar structures and background information on isatin as a biological agent, see Schutte et al. (2012); Garden et al. (2006); Goldschmidt & Llewellyn (1950); Frolova et al. (1988); Wei et al. (2004); Palmer et al. (1987); Akkurt et al. (2006). For reaction kinetic data on similar structures, see: Schutte et al. (2011).

Experimental top

5-(Trifluoromethoxy)isatin was dissolved in water (pH 4). The crystls were grown from a vapour diffusion setup with chloroform at 5 °C in a commercial refrigerator.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. Representation of the title compound, showing the numbering scheme and displacement ellipsoids (50% probability).
	Fig. 2. Observed π-π stacking (indicated by dashed lines) and packing in the crystal structure (hydrogen atoms omitted for clarity).

5-(trifluoromethoxy)-1H-indole-2,3-dione top

Crystal data top

C₉H₄F₃NO₃	F(000) = 928
M_r = 231.13	D_x = 1.728 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71069 Å
a = 14.329 (5) Å	Cell parameters from 9825 reflections
b = 6.082 (5) Å	θ = 2.8–28.2°
c = 20.401 (5) Å	µ = 0.17 mm⁻¹
β = 91.608 (5)°	T = 100 K
V = 1777.2 (16) Å³	Needle, orange
Z = 8	0.51 × 0.18 × 0.10 mm

Data collection top

Bruker APEXII CCD diffractometer	3513 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.029
ϕ and ω scans	θ_max = 28.3°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −19→19
T_min = 0.152, T_max = 0.394	k = −7→8
26198 measured reflections	l = −27→27
4428 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.102	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ²(F_o²) + (0.0458P)² + 0.9713P] where P = (F_o² + 2F_c²)/3
4418 reflections	(Δ/σ)_max = 0.001
297 parameters	Δρ_max = 0.34 e Å⁻³
0 restraints	Δρ_min = −0.33 e Å⁻³

Crystal data top

C₉H₄F₃NO₃	V = 1777.2 (16) Å³
M_r = 231.13	Z = 8
Monoclinic, P2₁/n	Mo Kα radiation
a = 14.329 (5) Å	µ = 0.17 mm⁻¹
b = 6.082 (5) Å	T = 100 K
c = 20.401 (5) Å	0.51 × 0.18 × 0.10 mm
β = 91.608 (5)°

Data collection top

Bruker APEXII CCD diffractometer	4428 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	3513 reflections with I > 2σ(I)
T_min = 0.152, T_max = 0.394	R_int = 0.029
26198 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.036	0 restraints
wR(F²) = 0.102	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	Δρ_max = 0.34 e Å⁻³
4418 reflections	Δρ_min = −0.33 e Å⁻³
297 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O2	0.44882 (8)	0.39123 (17)	0.43829 (5)	0.0258 (2)
O4	0.25592 (7)	0.62417 (16)	0.33404 (5)	0.0222 (2)
O3	0.41251 (8)	0.06479 (18)	0.69260 (5)	0.0255 (2)
O6	0.01035 (8)	−0.39384 (17)	0.38480 (5)	0.0258 (2)
N1	0.33820 (9)	−0.1165 (2)	0.43057 (6)	0.0207 (3)
F3	0.35956 (8)	0.40475 (15)	0.70118 (5)	0.0375 (3)
O5	0.21790 (7)	0.35661 (17)	0.44843 (5)	0.0230 (2)
F2	0.38339 (8)	0.20705 (17)	0.78654 (5)	0.0366 (2)
F5	−0.09269 (8)	−0.57440 (18)	0.43734 (6)	0.0482 (3)
O1	0.37037 (8)	0.09137 (17)	0.33911 (5)	0.0241 (2)
N2	0.16708 (9)	0.3571 (2)	0.28133 (6)	0.0202 (3)
C13	0.39620 (10)	0.1071 (2)	0.51369 (7)	0.0188 (3)
C14	0.34985 (10)	−0.0899 (2)	0.49875 (7)	0.0196 (3)
C11	0.37229 (10)	0.0574 (2)	0.39792 (7)	0.0202 (3)
C23	0.13214 (10)	0.1310 (2)	0.36813 (7)	0.0184 (3)
F6	−0.05978 (9)	−0.2481 (2)	0.46963 (6)	0.0564 (4)
C18	0.41720 (10)	0.1665 (2)	0.57812 (7)	0.0202 (3)
H18	0.449	0.2958	0.5885	0.024*
F1	0.26737 (7)	0.1395 (2)	0.72116 (5)	0.0436 (3)
F4	−0.13875 (8)	−0.2999 (2)	0.38080 (7)	0.0564 (4)
C15	0.32098 (11)	−0.2309 (2)	0.54708 (8)	0.0244 (3)
H15	0.2897	−0.361	0.5369	0.029*
C17	0.38837 (10)	0.0232 (2)	0.62607 (7)	0.0217 (3)
C26	0.03648 (10)	−0.1692 (2)	0.29098 (7)	0.0221 (3)
H26	0.0038	−0.2727	0.2659	0.027*
C24	0.12267 (10)	0.1618 (2)	0.30027 (7)	0.0190 (3)
C21	0.20969 (10)	0.4565 (2)	0.33289 (7)	0.0195 (3)
C28	0.09416 (10)	−0.0507 (2)	0.39831 (7)	0.0198 (3)
H28	0.101	−0.0734	0.4433	0.024*
C27	0.04544 (10)	−0.1968 (2)	0.35822 (7)	0.0209 (3)
C12	0.41347 (10)	0.2177 (2)	0.45094 (7)	0.0196 (3)
C29	−0.06921 (12)	−0.3765 (3)	0.41759 (9)	0.0324 (4)
C22	0.18838 (10)	0.3137 (2)	0.39389 (7)	0.0182 (3)
C25	0.07594 (10)	0.0119 (2)	0.26051 (7)	0.0217 (3)
H25	0.071	0.0311	0.2153	0.026*
C19	0.35582 (11)	0.2012 (3)	0.72439 (7)	0.0251 (3)
C16	0.34070 (11)	−0.1702 (2)	0.61182 (8)	0.0250 (3)
H16	0.3217	−0.2602	0.6458	0.03*
H1	0.3123 (13)	−0.224 (3)	0.4120 (9)	0.028 (5)*
H2	0.1668 (14)	0.403 (3)	0.2399 (11)	0.041 (6)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O2	0.0326 (6)	0.0228 (5)	0.0219 (5)	−0.0080 (4)	−0.0022 (4)	0.0025 (4)
O4	0.0266 (5)	0.0198 (5)	0.0204 (5)	−0.0040 (4)	0.0004 (4)	−0.0013 (4)
O3	0.0346 (6)	0.0267 (5)	0.0150 (5)	0.0069 (4)	−0.0031 (4)	0.0020 (4)
O6	0.0279 (6)	0.0206 (5)	0.0291 (6)	−0.0038 (4)	0.0033 (4)	0.0012 (4)
N1	0.0249 (6)	0.0178 (6)	0.0193 (6)	−0.0031 (5)	−0.0038 (5)	−0.0016 (5)
F3	0.0583 (7)	0.0238 (5)	0.0308 (5)	0.0088 (4)	0.0079 (5)	0.0058 (4)
O5	0.0240 (5)	0.0285 (5)	0.0165 (5)	−0.0019 (4)	−0.0021 (4)	−0.0034 (4)
F2	0.0518 (6)	0.0408 (6)	0.0171 (5)	0.0045 (5)	0.0000 (4)	0.0003 (4)
F5	0.0507 (7)	0.0394 (6)	0.0552 (7)	−0.0198 (5)	0.0141 (6)	0.0074 (5)
O1	0.0310 (6)	0.0246 (5)	0.0166 (5)	−0.0014 (4)	−0.0024 (4)	0.0000 (4)
N2	0.0259 (6)	0.0198 (6)	0.0147 (6)	−0.0021 (5)	−0.0011 (5)	−0.0005 (5)
C13	0.0205 (7)	0.0176 (6)	0.0183 (7)	0.0003 (5)	−0.0016 (5)	0.0016 (5)
C14	0.0205 (7)	0.0189 (6)	0.0192 (7)	0.0006 (5)	−0.0022 (5)	0.0001 (5)
C11	0.0207 (7)	0.0195 (6)	0.0203 (7)	0.0005 (5)	−0.0020 (5)	−0.0012 (5)
C23	0.0194 (7)	0.0192 (6)	0.0165 (7)	0.0011 (5)	−0.0008 (5)	−0.0029 (5)
F6	0.0623 (8)	0.0617 (8)	0.0470 (7)	−0.0306 (6)	0.0310 (6)	−0.0241 (6)
C18	0.0219 (7)	0.0194 (6)	0.0192 (7)	0.0003 (5)	−0.0023 (5)	0.0002 (5)
F1	0.0322 (6)	0.0599 (7)	0.0391 (6)	−0.0086 (5)	0.0089 (5)	−0.0075 (5)
F4	0.0260 (6)	0.0664 (8)	0.0766 (9)	0.0006 (5)	0.0004 (6)	0.0168 (7)
C15	0.0283 (8)	0.0179 (7)	0.0269 (8)	−0.0025 (6)	−0.0004 (6)	0.0020 (6)
C17	0.0264 (7)	0.0229 (7)	0.0157 (7)	0.0047 (6)	−0.0018 (5)	0.0015 (5)
C26	0.0215 (7)	0.0206 (7)	0.0241 (7)	0.0003 (5)	−0.0013 (6)	−0.0057 (6)
C24	0.0199 (7)	0.0187 (6)	0.0183 (7)	0.0017 (5)	0.0000 (5)	−0.0006 (5)
C21	0.0207 (7)	0.0195 (6)	0.0182 (7)	0.0018 (5)	0.0007 (5)	−0.0020 (5)
C28	0.0211 (7)	0.0210 (7)	0.0175 (7)	0.0009 (5)	0.0002 (5)	−0.0010 (5)
C27	0.0203 (7)	0.0178 (6)	0.0247 (7)	−0.0001 (5)	0.0028 (6)	−0.0006 (5)
C12	0.0201 (7)	0.0204 (7)	0.0181 (7)	−0.0004 (5)	−0.0027 (5)	−0.0001 (5)
C29	0.0317 (9)	0.0316 (8)	0.0340 (9)	−0.0095 (7)	0.0050 (7)	−0.0019 (7)
C22	0.0183 (6)	0.0189 (6)	0.0173 (7)	0.0019 (5)	0.0008 (5)	−0.0019 (5)
C25	0.0240 (7)	0.0232 (7)	0.0178 (7)	0.0000 (6)	−0.0023 (5)	−0.0027 (5)
C19	0.0300 (8)	0.0260 (7)	0.0193 (7)	0.0010 (6)	0.0015 (6)	0.0043 (6)
C16	0.0316 (8)	0.0203 (7)	0.0233 (8)	0.0015 (6)	0.0028 (6)	0.0069 (6)

Geometric parameters (Å, º) top

O2—C12	1.2017 (19)	C11—C12	1.560 (2)
O4—C21	1.2157 (19)	C23—C28	1.384 (2)
O3—C19	1.3410 (19)	C23—C24	1.400 (2)
O3—C17	1.4140 (18)	C23—C22	1.462 (2)
O6—C29	1.342 (2)	F6—C29	1.322 (2)
O6—C27	1.4134 (19)	C18—C17	1.382 (2)
N1—C11	1.349 (2)	C18—H18	0.93
N1—C14	1.4055 (19)	F1—C19	1.322 (2)
N1—H1	0.84 (2)	F4—C29	1.316 (2)
F3—C19	1.327 (2)	C15—C16	1.393 (2)
O5—C22	1.2078 (17)	C15—H15	0.93
F2—C19	1.3180 (18)	C17—C16	1.387 (2)
F5—C29	1.316 (2)	C26—C27	1.384 (2)
O1—C11	1.2170 (18)	C26—C25	1.393 (2)
N2—C21	1.3450 (18)	C26—H26	0.93
N2—C24	1.407 (2)	C24—C25	1.381 (2)
N2—H2	0.89 (2)	C21—C22	1.555 (2)
C13—C18	1.388 (2)	C28—C27	1.383 (2)
C13—C14	1.399 (2)	C28—H28	0.93
C13—C12	1.473 (2)	C25—H25	0.93
C14—C15	1.379 (2)	C16—H16	0.93

C19—O3—C17	116.08 (12)	C23—C24—N2	110.67 (12)
C29—O6—C27	116.17 (12)	O4—C21—N2	128.85 (14)
C11—N1—C14	111.35 (12)	O4—C21—C22	124.91 (13)
C11—N1—H1	123.4 (13)	N2—C21—C22	106.24 (12)
C14—N1—H1	125.2 (13)	C27—C28—C23	116.62 (13)
C21—N2—C24	111.32 (12)	C27—C28—H28	121.7
C21—N2—H2	126.2 (14)	C23—C28—H28	121.7
C24—N2—H2	122.4 (14)	C28—C27—C26	122.61 (14)
C18—C13—C14	121.22 (13)	C28—C27—O6	119.79 (13)
C18—C13—C12	131.81 (13)	C26—C27—O6	117.33 (13)
C14—C13—C12	106.98 (12)	O2—C12—C13	132.05 (13)
C15—C14—C13	121.78 (14)	O2—C12—C11	123.61 (13)
C15—C14—N1	127.34 (14)	C13—C12—C11	104.33 (12)
C13—C14—N1	110.88 (12)	F5—C29—F4	107.62 (14)
O1—C11—N1	128.44 (13)	F5—C29—F6	108.41 (15)
O1—C11—C12	125.11 (13)	F4—C29—F6	107.90 (16)
N1—C11—C12	106.43 (12)	F5—C29—O6	108.00 (14)
C28—C23—C24	121.25 (13)	F4—C29—O6	112.56 (15)
C28—C23—C22	131.81 (13)	F6—C29—O6	112.18 (14)
C24—C23—C22	106.91 (12)	O5—C22—C23	132.15 (13)
C17—C18—C13	116.42 (13)	O5—C22—C21	123.01 (13)
C17—C18—H18	121.8	C23—C22—C21	104.81 (12)
C13—C18—H18	121.8	C24—C25—C26	117.14 (14)
C14—C15—C16	117.14 (14)	C24—C25—H25	121.4
C14—C15—H15	121.4	C26—C25—H25	121.4
C16—C15—H15	121.4	F2—C19—F1	108.46 (13)
C18—C17—C16	122.79 (14)	F2—C19—F3	107.71 (13)
C18—C17—O3	119.79 (13)	F1—C19—F3	107.18 (13)
C16—C17—O3	117.31 (13)	F2—C19—O3	108.22 (13)
C27—C26—C25	120.73 (13)	F1—C19—O3	113.15 (14)
C27—C26—H26	119.6	F3—C19—O3	111.94 (13)
C25—C26—H26	119.6	C17—C16—C15	120.63 (14)
C25—C24—C23	121.63 (13)	C17—C16—H16	119.7
C25—C24—N2	127.70 (13)	C15—C16—H16	119.7

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4ⁱ	0.84 (2)	1.99 (2)	2.7615 (18)	152.8 (18)
N2—H2···O1ⁱⁱ	0.89 (2)	2.03 (2)	2.8776 (18)	157.4 (19)
N2—H2···O4ⁱⁱⁱ	0.89 (2)	2.55 (2)	2.9850 (18)	111.2 (16)
C16—H16···F3ⁱ	0.93	2.39	3.171 (2)	142
C18—H18···O2^iv	0.93	2.47	3.327 (3)	153

Symmetry codes: (i) x, y−1, z; (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x+1/2, y−1/2, −z+1/2; (iv) −x+1, −y+1, −z+1.

Experimental details

Crystal data
Chemical formula	C₉H₄F₃NO₃
M_r	231.13
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	14.329 (5), 6.082 (5), 20.401 (5)
β (°)	91.608 (5)
V (Å³)	1777.2 (16)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.17
Crystal size (mm)	0.51 × 0.18 × 0.10

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.152, 0.394
No. of measured, independent and observed [I > 2σ(I)] reflections	26198, 4428, 3513
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.668

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.102, 1.04
No. of reflections	4418
No. of parameters	297
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.34, −0.33

Computer programs: APEX2 (Bruker, 2008), SAINT-Plus (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4ⁱ	0.84 (2)	1.99 (2)	2.7615 (18)	152.8 (18)
N2—H2···O1ⁱⁱ	0.89 (2)	2.03 (2)	2.8776 (18)	157.4 (19)
N2—H2···O4ⁱⁱⁱ	0.89 (2)	2.55 (2)	2.9850 (18)	111.2 (16)
C16—H16···F3ⁱ	0.93	2.39	3.171 (2)	142.1
C18—H18···O2^iv	0.93	2.47	3.327 (3)	152.9

Symmetry codes: (i) x, y−1, z; (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x+1/2, y−1/2, −z+1/2; (iv) −x+1, −y+1, −z+1.

Acknowledgements

The University of the Free State, the Chemistry Department, the NRF and SASOL Ltd are acknowledged for funding.

References

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